Electromagnetic pump for liquid metals

ABSTRACT

An electromagnetic pump comprising an impelling duct for liquid metals having a symmetry axis, made of a refractory material and equipped with preheating means and thermal insulation, a stator consisting of two magnetic yokes arranged on both sides of the duct and comprising laminated cores in parallel relation to a plane containing the axis of the duct and having deep and uniformly spaced slots, each of which receives a flat coil in a direction perpendicular to the axis of the duct. In this manner, each of the coils can be removed by translation in a direction parallel to the axis of the duct after unclamping in a perpendicular direction.

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ELECTROMAGNE'MQ PUMP FUR LIQUID METALS Inventors: Henri Carbonnel,Anthony; Jean Le Fret-e,

Villejuif, both of France Groupeme'nt 'Atomique Alsacienne Atlantique,Plessis Robinson, France Filed: July 15, 1970 Appl. No.: 54,946

Assignee:

[30] Foreign Application Priority Data July 16, 1969 France ..6924241[52] U.S.Cl ..4l7/50,310/l1,310/259 Int. Cl. ..H02n 4/20, H02k 45/00,621d 7/02, H02k 1/12 Field of Search ..417/50; 310/1 1, 254, 258, 259,310/260 References Cited UNITED STATES PATENTS 2,764,095 9/1956 Baker..417/50 3,005,116 10/1961 Reece ..417/50X Primary Examiner-Robert M.Walker Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Anelectromagnetic pump comprising an impelling duct for liquid metalshaving a symmetry axis, made of a refractory material and equipped withpreheating means and thermal insulation, a stator consisting of twomagnetic yokes arranged on both sides of the duct and comprisinglaminated cores in parallel relation to a plane containing the axis ofthe duct and having deep and uniformly spaced slots, each of whichreceives a flat coil in a direction perpendicular to the axis of theduct. In this manner, each of the coils can be removed by translation ina direction parallel to the axis of the duct after unclamping in aperpendicular direction.

3 Claims, Z'Drawing Figures- ELECTROMAGNETIC PUMP FOR LIQUID METALSBACKGROUND OF THE INVENTION This invention involves an improvement inelectromagnetic pumps employed for impelling liquid metals.

Electromagnetic pumps of a known type generally consist in principle ofa magnetic circuit and a metal duct, e.g., of stainless steel. Suchpumps are known to be unable to impel such ordinary metals as zinc oraluminum because the latter attack the metal or alloy of the pump duct.In the French Pat. PV 127,426 of 1 July 1968, the inventors alreadysuggested making the impelling duct of a refractory material provided onthe outside with a metal layer facilitating preheating of the duct. Thisprevents the duct both being attacked by the usual metals and alsoeliminates the risk of solidification of the metal in the piping duringdischarge of the metal.

This solution leads, however, to some difficulties caused by theincrease of the air gap between stators. This makes it necessary toprovide thermal insulation for the heating device of the refractory ductfrom against the environment and may also require protection of therefractory duct against the chemical action of the environment bycovering it with a metal sheath resistant to oxidation at hightemperature as described by the petitioner in French Pat. No. 69 42 788of Dec. 1969 and the amendment No. 69 45 218 of 29 December 1969 to thispatent. Induction heating of the metal sheath on the outside of the ductfor the liquid metal may be further aided by winding heated conductorsof any known type around it. The air gap is thus ultimately multipliedby a factor of 5 in relation to pumps of standard type. In order toimpel the liquid metal, sufficient magnetic induction must be maintainedwithin the duct. Accordingly, the number of ampereturns applied to themagnetic circuit per unit length of pump must be increased. If this isdone by using standard procedures, we then have to arrange for wide anddeep slots in the magnetic core utilized. Consequently, the involutesbetween successive pole tips would assume too large a volume. In pumpsfor ordinary metals such as aluminum, it is also advantageous to utilizea duct where the ratio between the width of duct (its largest dimension)and its thickness (its smallest dimension) is relatively low. Since thethickness of the laminated cores of the magnetic circuit does not exceedthe width of the duct (its largest dimension), it is not possible as aresult of this to increase the active volume of the magnetic circuit.

SUMMARY OF THE INVENTION The present invention provides an originaldesign for the stators of electromagnetic pumps in order to remedy theabove disadvantages and imperfections.

It has been noted that, wherever a failure occurs in the operation ofthe pump, it may be necessary to provide rapid access to the duct of thepump before discharge is arrested and the metal solidifies in thepiping. It therefore appeared absolutely necessary to construct pumpswith coils whose involutes occupy as small a volume as possible and can,at the same time, be disassembled rapidly by a sequence of very simplesteps.

This invention involves an improved electromagnetic pump constituted byan impelling duct for liquid metals presenting a symmetry axis, made ofrefractory material and equipped with means for preheating and thermalinsulation; a stator consisting of two magnetic yokes arranged on bothsides of the duct and constituted by laminated cores placed parallel toa plane containing the axis of the duct and having deep and uniformlyspaced slots each of which holds a Hat coil perpendicular to the axis ofthe duct where each of these coils can be removed by translation in adirection parallel to the axis of the duct after unclamping in aperpendicular direction.

In order to lower costs and fabricate, according to the same method,several types of pumps suitable for different users, each yoke comprisesidentical elements with two or three slots depending on whether the pumpis powered by single-phase or three-phase current. This makes itpossible to constitute as many independent identical elements with twoor three coils where these elements are assembled to each other by anyappropriate means.

An improved magnetic pump in accordance with the present invention ischaracterized in that the yoke of each of the magnetic circuits is madeof independent elements having as many coils as slots where theseelements are assembled to each other by any appropriate means.

This device makes it possible to construct compact coils with a largenumber of ampere-turns around a yoke element and to assemble the desirednumber of such standard elements in order to adapt the length of thestator to the characteristics of the electromagnetic pump.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of anelectromagnetic pump according to this invention; and

FIG. 2 is a top plan view of the pump shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, anelectromagnetic pump for particularly corrosive liquid metalsconstructed in accordance with the present invention, comprises a tube 1made of an insulating and refractory material e.g. graphite) with ametal sheath 2 resistant to oxidation and having high electricresistance, and a concentric envelope 3 constituted of athermal-insulation material for protecting the magnetic circuit againstthe heat of the liquid metal. In order to simplify the drawing, theheating elements for preheating the tube prior to introducing the liquidmetal are not shown. The tube 1 also is slightly tapered to facilitateremoval of solidified metal in case of failure. The whole is suitablyarranged on a cradle mounted on the base 5 of the pump by anyappropriate means.

On either side of the tube 1 are arranged two identical magneticcircuits constituted each by a magnetic yoke 6 with slots 7 (FIG. 2) andof a number of coils 8 fitting into these slots. Each of the magneticcircuits is placed in a ventilation duct 9 to which fresh air issupplied through the ducts l0 and 11. Electric power is supplied to thecoils 8 through cable 12 across a junction box 13.

FIG. 2 shows certain details and components not described in referenceto FIG. 1. Specifically, it shows the extremity of the slots 7 of themagnetic yoke described in the preceding figure and also the coilsengaged in these slots.

Where the magnetic yoke 6 of each of the magnetic circuits consists of anumber of elements, the latter are assembled to each other by means of athreaded rod 15, or a bar threaded at the ends, and two terminal nuts14. They can also be assembled with dovetailed devices or' with U-shapedrods (not shown) sliding in seats provided in the yoke where theelements are assembled by the pressure of a nut at each end. Each of themagnetic yoke elements, therefore, has one or more slots in which areengaged one or more coils.

All things being equal, this type of construction permits a considerablereduction on the volume of the coils and appreciable savings in theconsumption of electric power.

The electromagnetic pump of this invention has the advantage of beingeasily disassembled, which permits rapid access either to tube 1 incases where the liquid metal has solidified or any other failure, or tothe magnetic circuit when it is desired to replace a defective coil.

In order to obtain access to tube 1, it is only necessary to remove theventilation ducts 9 and to displace the magnetic circuits laterally.

When it is desired to dismount the coils of one of the magnetic circuit,it is only necessary, after having removed this circuit from tube l, toslip each of the coils 8 out of the corresponding slot 7 in which it isengaged, by pushing it in the direction of the arrow F when it can bewithdrawn by sliding it along the yoke 6.

By reason of mechanical necessity, it may become necessary to increasethe thickness of the metal sheath of the tube, and possibly greatlyreduce the thickness of the tube of refractory material in cases wherethe impelled materials are not highly corrosive.

We claim:

1. An electromagnetic pump comprising an impelling duct for liquidmetals having a symmetry axis and being made of a refractory material,said duct having means for preheating the refractory material; and astator formed of two yokes arranged on either side of said duct, saidyokes each comprising a laminated core arranged parallel to a planecontaining the symmetry axis of said duct and provided with deep slotsfacing the duct and uniformly spaced along the duct, and a flat coileach other.

3. The pump as in claim 1 in which the duct is surrounded by thermalinsulation material for protecting the coils against the heat of theliquid metal.

1. An electromagnetic pump comprising an impelling duct for liquidmetals having a symmetry axis and being made of a refractory material,said duct having means for preheating the refractory material; and astator formed of two yokes arranged on either side of said duct, saidyokes each comprising a laminated core arranged parallel to a planecontaining the symmetry axis of said duct and provided with deep slotsfacing the duct and uniformly spaced along the duct, and a flat coilperpendicular to the symmetry axis mounted in each of said slots,whereby said coils can be removed by translation in a direction parallelto the axis of the duct after removing them from the slots in adirection perpendicular to the axis of the duct.
 2. The pump as in claim1 in which each of said yokes is made of a plurality of independentelements defining said slots, and means are provided for assembling saidelements to each other.
 3. The pump as in claim 1 in which the duct issurrounded by thermal insulation material for protecting the coilsagainst the heat of the liquid metal.